1. Field of the Invention
The present invention concerns a method of allocating a service by a first peer to a second peer.
It also concerns an allocation device adapted to implement the method according to the invention.
2. Brief Description of the Related Art
In general terms, the present invention concerns the communication of electronic files, and in particular digital images, on communication networks.
More precisely, the present invention concerns communication networks having a peer-to-peer (or station-to-station) architecture.
In this type of network, several computers are connected together and each computer or terminal can be both server or client on the communication network. In such a communication network, the data are stored in a distributed fashion, the place of storage then being able to be considered to be almost unlimited.
In such a system, each terminal is identified uniquely. One or more users are associated with each terminal. Conversely, a given user can be connected through the peer-to-peer network from several terminals. Each user is also identified uniquely by means for example of an electronic address.
Each terminal and a user of the network thus forms a peer in the network. It should be noted here that several peers in the network can be connected to the same user.
Each peer belongs to a group of peers adapted to share data.
By way of example, such a communication and data exchange system is encountered in particular in the context of the exchange of personal digital data, of the network type referred to in English as F2F (or “Friends to Family”).
In such a communication network, the main drawback compared with a “client-server” model is that the server or servers for a content requested on the network is or are not always connected.
It is therefore advantageous to store the data in a redundant fashion on several terminals so as to be able to satisfy a data request, even if the source of the initial data is not connected.
In parallel, in this type of network in which the data are not public, it is desirable to preserve these data and to leave, at the choice of the user, the possibility of allocating the service of all or some of its data.
In particular, in a group of peers as defined above, each peer has the possibility of sharing a set of data, also referred to as a collection, with a subset of peers which it knows, several of these peers possibly being able to represent the same user.
In addition, at each terminal, a user has the possibility of recreating a collection from data received, by mixing for example data received from various sources.
This collection will once again be shared with other peers forming part of the group of peers to which this second peer belongs.
In such a system, access to the content of the data is therefore not controlled by the initial possessor of the data.
It is thus necessary in such a network to allow access to shared data, even when the source terminal for these data is disconnected from the network, whilst at the same time restricting this access in order to protect the rights of each peer sharing these data.
A completely distributed digital document communication system is known, functioning without a central server; this communication system, known as GNUTELLA, is adapted to propagate each content request emanating from terminal to the connected adjacent terminals, with a predetermined depth within the connection graphic.
A description of this GNUTELLA system will be found in the document entitled “File Sharing Protocols: a Tutorial on Gnutella”, V. Berg and G. Cybenko, March 2001, Technical report, Institute for Security Technology Studies, Darmouth College, Hanover, USA.
This depth is either fixed as a parameter of the system, or fixed by the user of the terminal initiating the content request.
Consequently the server peers do not have direct control over this parameter.
In addition, since it is a case of the propagation of a request in a connection graphic of the communication network, a disconnected node may compromise the obtaining of the result.